Clinical studies of histone deacetylase inhibitors

EX527, a sirtuins 1 inhibitor, sensitizes T-cell leukemia to death receptor-mediated apoptosis by downregulating cellular FLICE inhibitory protein

Death receptor-mediated extrinsic apoptosis system had been developed as a promising therapeutic strategy in clinical oncology, such as TRAIL therapy. However, multiple studies have demonstrated that TRAIL resistance is the biggest problem for disappointing clinical trials despite preclinical success. Targeting cellular FLICE inhibitory protein (cFLIP) is one strategy of combinatorial therapies to overcome resistance to DR-mediated apoptosis due to its negative regulator of extrinsic apoptosis. E × 527 (Selisistat) is a specific inhibitor of SIRT1 activity with safe and well tolerance in clinical trials. Here, we show that E × 527 could strengthen significantly activation of rhFasL-mediated apoptotic signaling pathway and increased apoptotic rate of T leukemia cells with high expression of cFLIP. Mechanically, Inhibition of SIRT1 by E × 527 increased polyubiquitination level of cFLIP via increasing acetylation of Ku70, which could promote proteosomal degradation of cFLIP protein. It implied that combinatorial therapies of E × 527 plus TRAIL may have a potential as a novel clinical application for TRAIL-resistant hematologic malignancies.

Proteomics analysis of histone deacetylase inhibitor-resistant solid tumors reveals resistant signatures and potential drug combinations

Histone deacetylase inhibitors (HDACis) are important drugs for cancer therapy, but the indistinct resistant mechanisms of solid tumor therapy greatly limit their clinical application. In this study we conducted HDACi-perturbated proteomics and phosphoproteomics analyses in HDACi-sensitive and -resistant cell lines using a tandem mass tag (TMT)-based quantitative proteomic strategy. We found that the ribosome biogenesis proteins MRTO4, PES1, WDR74 and NOP16 vital to tumorigenesis might regulate the tumor sensitivity to HDACi. By integrating HDACi-perturbated protein signature with previously reported proteomics and drug sensitivity data, we predicted and validated a series of drug combination pairs potentially to enhance the sensitivity of HDACi in diverse solid tumor. Functional phosphoproteomic analysis further identified the kinase PDK1 and ROCK as potential HDACi-resistant signatures. Overall, this study reveals the potential HDACi-resistant signatures and may provide promising drug combination strategies to attenuate the resistance of solid tumor to HDACi.

A Novel Liver Cancer-Selective Histone Deacetylase Inhibitor Is Effective Against Hepatocellular Carcinoma and Induces Durable Responses with Immunotherapy

Hepatocellular cancer (HCC) progression is facilitated by gene-silencing chromatin histone hypoacetylation due to histone deacetylases (HDACs) activation. However, inhibiting HDACs, an effective treatment for lymphomas, has shown limited success in solid tumors. We report the discovery of a class of HDAC inhibitors (HDACi) that demonstrates exquisite selective cytotoxicity against human HCC cells. The lead compound STR-V-53 (3) showed favorable safety profile in mice and robustly suppressed tumor growth in orthotopic xenograft models of HCC. When combined with the anti-HCC drug sorafenib, STR-V-53 showed greater in vivo efficacy. Moreover, STR-V-53 combined with anti-PD1 therapy increased the CD8+ to regulatory T-cell (Treg) ratio and survival in an orthotopic HCC model in immunocompetent mice. This combination therapy resulted in durable responses in 40% of the mice. Collectively, our data demonstrate that the novel HDACi STR-V-53 is an effective anti-HCC agent that can induce profound responses when combined with standard immunotherapy.

Discovery of YSR734: A Covalent HDAC Inhibitor with Cellular Activity in Acute Myeloid Leukemia and Duchenne Muscular Dystrophy

Histone deacetylases (HDACs) have emerged as powerful epigenetic modifiers of histone/non-histone proteins via catalyzing the deacetylation of ε-N-acetyl lysines. The dysregulated activity of these Zn2+-dependent hydrolases has been broadly implicated in disease, notably cancer. Clinically, the recurring dose-limiting toxicities of first-generation HDACi sparked a paradigm shift toward safer isoform-specific molecules. With pervasive roles in aggressive diseases, there remains a need for novel approaches to target these enzymes. Herein, we report the discovery of YSR734, a first-in-class covalent HDACi, with a 2-aminobenzanilide Zn2+ chelate and a pentafluorobenzenesulfonamide electrophile. This class I selective proof of concept modified HDAC2Cys274 (catalytic domain), with nM potency against HDAC1-3, sub-μM activity in MV4-11 cells, and limited cytotoxicity in MRC-9 fibroblasts. In C2C12 myoblasts, YSR734 activated muscle-specific biomarkers myogenin/Cav3, causing potent differentiation into myotubes (applications in Duchenne Muscular Dystrophy). Current efforts are focused on improving in vivo ADME toward a preclinical covalent HDACi.

Novel therapeutic approaches to target neurodegeneration

Ageing is the main risk factor common to most primary neurodegenerative disorders. Indeed, age-related brain alterations have been long considered to predispose to neurodegeneration. Although protein misfolding and the accumulation of toxic protein aggregates have been considered as causative events in neurodegeneration, several other biological pathways affected by brain ageing also contribute to pathogenesis. Here, we discuss the evidence showing the involvement of the mechanisms controlling neuronal structure, gene expression, autophagy, cell metabolism and neuroinflammation in the onset and progression of neurodegenerative disorders. Furthermore, we review the therapeutic strategies currently under development or as future approaches designed to normalize these pathways, which may then increase brain resilience to cope with toxic protein species. In addition to therapies targeting the insoluble protein aggregates specifically associated with each neurodegenerative disorder, these novel pharmacological approaches may be part of combined therapies designed to rescue brain function.

Mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are a distinct disease entity of cutaneous T-cell lymphoma with heterogenous clinical features and prognosis. MF mainly involves skin and usually shows an indolent and favorable clinical course. In patients with advanced-stage disease, extracutaneous involvement including lymph nodes, viscera, and blood, or large cell transformation may be observed. SS is a leukemic form of advanced-stage MF, characterized by generalized erythroderma. Early-stage MF can be treated with skin-directed therapy. However, patients with refractory or advanced-stage disease are associated with severe symptoms or poor prognosis, requiring systemic therapy. Recent progress in understanding the pathogenesis of MF/SS has contributed to advances in the management of these rare diseases. This review aims to describe the clinical manifestations, diagnosis, risk stratification, and treatment strategy of MF/SS, focusing on the recent updates in the management of these diseases.

Design, Synthesis and Bioactivity Evaluations of 8-Substituted-Quinoline-2-Carboxamide Derivatives as Novel Histone Deacetylase (HDAC) Inhibitors

The inhibition of histone deacetylases (HDACs) has been considered a promising therapeutic strategy for treatment of many diseases, especially cancer. In the current study, a series of 8-substituted quinoline-2-carboxamide derivatives were designed and synthesized as potent HDAC inhibitors. The most potent compound 21 g (IC₅₀ = 0.050 µM) exhibited 3-fold greater HDAC inhibitory activity compared to the known HDAC inhibitor Vorinostat (IC₅₀ = 0.137 µM). Additionally, compound 21g exhibited low toxicity against normal cells(IC₅₀ in HUVEC cell > 50 µM) and showed good liver microsomal stability, therefore, may serve as a new lead compound for further development.

Panobinostat inhibits breast cancer progression via Vps34-mediated exosomal pathway

Exosomes play crucial roles in intercellular communication, including tumor metastasis. Panobinostat (LBH589), a histone deacetylases (HDAC) inhibitor, is an emerging anti-tumor drug with promising efficacy in cancer therapy. This study was set out from recent evidence that exosome was a mechanism of intercellular drug transfer with significant pharmacological consequences. It enlightened us LBH589 might regulate tumor growth through exosomal secretion. Here we demonstrated LBH589 induced autophagy and facilitated secretory autophagy. Furthermore, LBH589 dose- and time-dependently stimulated exosomal release mediated by Vps34/Rab5C pathway, documented by the ablation of Vps34 and/or Rab5C in breast cancer cells. Additionally, the findings also presented LBH589 inhibited breast cancer progression via exosomes. Altogether, we revealed a novel mechanism of LBH589 in exosome-mediated anti-tumor effects in breast cancer. The schematic diagram of signaling pathways involved in the suppression of breast cancer progression by LBH589 via exosomes.

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Clinical and immune correlate results from a phase 1b study of the histone deacetylase inhibitor mocetinostat with ipilimumab and nivolumab in unresectable stage III/IV melanoma

Checkpoint immunotherapies (CPIs) have improved outcomes for metastatic melanoma patients, with objective response rates to combination ipilimumab and nivolumab of ~58%. Preclinical data suggest that histone deacetylase (HDAC) inhibition enhances antitumor immune activity and may augment CPI. In a phase Ib open-label pilot trial (NCT03565406), patients with therapy-naive metastatic melanoma were treated with the class I/IV HDAC inhibitor mocetinostat orally three times a week in combination with nivolumab and ipilimumab every 3 weeks for 12 weeks followed by 12-week maintenance cycles of nivolumab every 2 weeks and mocetinostat at the same dose and schedule as induction. The endpoints of the trial were safety, definition of a recommended phase 2 dose, preliminary assessment of response, and correlative marker determination. Patient PBMC and serum samples collected at baseline and on-treatment were assessed by flow cytometry and Luminex assays for immune correlates. Ten patients were treated: nine with 70-mg and one with 50-mg mocetinostat. In the 70-mg cohort, eight patients had objective responses. The patient in the 50-mg cohort had an early progression of disease. All patients had grade 2 or higher toxicities, and six had grades 3 and 4 toxicities. Patient PBMC showed significant decreases in myeloid-derived suppressor cells and trends towards reduced anti-inflammatory monocyte phenotypes. Patient serum showed significant upregulation of granzyme A and TNF and trends towards increased granzyme B and IFNγ. Collectively, combining CPI and mocetinostat had favorable response rates but with high levels of toxicity. Assessment of immune correlates supports a shift away from immunosuppressive phenotypes towards enhanced immune responses.

Cyclin-Dependent Kinase Inhibitors Function as Potential Immune Regulators via Inducing Pyroptosis in Triple Negative Breast Cancer

Background

Immunotherapy is the most promising treatment in triple-negative breast cancer (TNBC), and its efficiency is largely dependent on the intra-tumoral immune cells infiltrations. Thus, novel ways to assist immunotherapy by increasing immune cell infiltrations were highly desirable.

Methods

To find key immune-related genes and discover novel immune-evoking molecules, gene expression profiles of TNBC were downloaded from Gene Expression Omnibus (GEO). Single-sample gene set enrichment analysis (ssGSEA) and Weighted Gene Co-expression Network Analysis (WGCNA) were conducted to identified hub genes. The CMap database was used subsequently to predicate potential drugs that can modulate the overall hub gene expression network. In vitro experiments were conducted to assess the anti-tumor activity and the pyroptosis phenotypes induced by GW-8510.

Results

Gene expression profiles of 198 TNBC patients were downloaded from GEO dataset GSE76124, and ssGSEA was used to divide them into Immune Cell Proficiency (ICP) group and Immune Cell Deficiency (ICD) group. Hub differential expressed gene modules between two groups were identified by WGCNA and then annotated by Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. A cyclin-dependent kinase (CDK) 2 inhibitor, GW-8510 was then identified by the CMap database and further investigated. Treatment with GW-8510 resulted in potent inhibition of TNBC cell lines. More importantly, in vitro and in vivo studies confirmed that GW-8510 and other CDK inhibitors (Dinaciclib, and Palbociclib) can induce pyroptosis by activating caspase-3 and GSDME, which might be the mechanism for their immune regulation potentials.

Conclusion

GW-8510, as well as other CDK inhibitors, might serve as potential immune regulators and pyroptosis promotors in TNBC.

Epigenetic silencing of E-cadherin gene induced by lncRNA MALAT-1 in acute myeloid leukaemia

Background

Epigenetic abnormalities in acute myeloid leukaemia provide us with a target for novel therapeutic strategies. The aim of the study was to verify the epigenetic regulatory mechanism of E‐cadherin gene silencing induced by long non‐coding RNA MALAT‐1 in AML.

Methods

Expression of MALAT‐1, E‐cadherin, EZH2, SUZ12 and EED genes in AML patients was detected by RT‐qPCR. After MALAT‐1 silencing in AML cell lines, levels of the E‐cadherin, EZH2, SUZ12, EED, DNMT1, DNMT3A and DNMT3B genes and encoded proteins were detected by RT‐qPCR and Western blotting. The level of CpG island methylation and trimethylation modification of histone H3K27 in the promoter region of E‐cadherin was detected by pyrosequencing and ChIP‐qPCR. RIP‐qPCR was used to detect the interaction between MALAT‐1 and proteins.

Results

MALAT‐1, EZH2 and EED gene expression was markedly increased in AML patients with E‐cadherin down‐regulation. A positive correlation between EZH2 or SUZ12 and MALAT‐1 expression was observed. After MALAT‐1 silencing, the expression of E‐cadherin was up‐regulated, whereas the expression of EZH2, SUZ12, DNMT1, DNMT3A and DNMT3B was down‐regulated. Results of Western blotting were consistent with those of RT‐qPCR. Methylation levels of E‐cadherin in AML patients were higher than that in normal controls, which appeared to increase with age. Methylation of the CpG island and H3K27 trimethylation of E‐cadherin were decreased after MALAT‐1 silencing. RIP‐qPCR suggested that MALAT‐1 might be enriched by EZH2 and SUZ12.

Conclusion

Our findings verified that MALAT‐1 might lead to the transcriptional silencing of E‐cadherin gene through the trimethylation of H3K27 mediated by recruiting EZH2 and SUZ12.

The New Treatment Methods for Non-Hodgkin Lymphoma in Pediatric Patients

One of the most common cancer malignancies is non-Hodgkin lymphoma, whose incidence is nearly 3% of all 36 cancers combined. It is the fourth highest cancer occurrence in children and accounts for 7% of cancers in patients under 20 years of age. Today, the survivability of individuals diagnosed with non-Hodgkin lymphoma varies by about 70%. Chemotherapy, radiation, stem cell transplantation, and immunotherapy have been the main methods of treatment, which have improved outcomes for many oncological patients. However, there is still the need for creation of novel medications for those who are treatment resistant. Additionally, more effective drugs are necessary. This review gathers the latest findings on non-Hodgkin lymphoma treatment options for pediatric patients. Attention will be focused on the most prominent therapies such as monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T cell therapy and others.

Histone Deacetylase 2 Knockdown Ameliorates Morphological Abnormalities of Dendritic Branches and Spines to Improve Synaptic Plasticity in an APP/PS1 Transgenic Mouse Model

Disease-modifying therapies, such as neuroprotective and neurorestorative interventions, are strongly desired for Alzheimer’s disease (AD) treatment. Several studies have suggested that histone deacetylase 2 (HDAC2) inhibition can exhibit disease-modifying effects in AD patients. However, whether HDAC2 inhibition shows neuroprotective and neurorestorative effects under neuropathic conditions, such as amyloid β (Aβ)-elevated states, remains poorly understood. Here, we performed HDAC2-specific knockdown in CA1 pyramidal cells and showed that HDAC2 knockdown increased the length of dendrites and the number of mushroom-like spines of CA1 basal dendrites in APP/PS1 transgenic mouse model. Furthermore, HDAC2 knockdown also ameliorated the deficits in hippocampal CA1 long-term potentiation and memory impairment in contextual fear conditioning tests. Taken together, our results support the notion that specific inhibition of HDAC2 has the potential to slow the disease progression of AD through ameliorating Aβ-induced neuronal impairments.

Cutaneous T-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Epigenetic Targeting of Histone Deacetylases in Diagnostics and Treatment of Depression

Depression is a highly prevalent, disabling, and often chronic illness that places substantial burdens on patients, families, healthcare systems, and the economy. A substantial minority of patients are unresponsive to current therapies, so there is an urgent need to develop more broadly effective, accessible, and tolerable therapies. Pharmacological regulation of histone acetylation level has been investigated as one potential clinical strategy. Histone acetylation status is considered a potential diagnostic biomarker for depression, while inhibitors of histone deacetylases (HDACs) have garnered interest as novel therapeutics. This review describes recent advances in our knowledge of histone acetylation status in depression and the therapeutic potential of HDAC inhibitors.

Association between histone deacetylase activity and vitamin D-dependent gene expressions in relation to sulforaphane in human colorectal cancer cells

BACKGROUND

It is relatively unknown as to how dietary bioactive compound sulforaphane (SFN) and vitamin D regulate gene expression in colorectal cancer. We hypothesized that a combination of SFN with vitamin D would prove beneficial in colorectal cancer. A combinatorial chemo-preventive strategy was employed to investigate the impact of SFN on chromatin remodeling in colorectal carcinoma. To understand the epigenetics-mediated changes in gene expression in response to SFN and vitamin D, Caco-2 cells were exposed for 24 h to vitamin D (100 nmol L^-1 ) either alone or in combination with SFN and trichostatin A (20 and 1 μmol L^-1 , respectively) at 70% confluency (proliferating) and after 13 days post-confluency (fully differentiated). Changes to VDR, CYP24A1, CYP27B1 and TRPV6 gene expressions were quantified using real-time PCR-based assays. Histone deacetylase (HDAC) inhibitor activity was assessed using HDAC I/II assay that measured global changes in acetylation status.

RESULTS

In differentiated Caco-2 cells, none of the genes had significant changes from D alone group. D + SFN (P = 0.99) demonstrated an opposing effect from D alone and decreased VDR expression. However, in proliferating Caco-2 cells, D + SFN (P < 0.04) increased VDR expression and decreased CYP27B1 (P < 0.01) more than D alone (P = 0.38 and 0.07, respectively). Although statistically significant, D + SFN (P = 0.01) effect on HDAC inhibitor activity was less than trichostatin A alone group (P < 0.0004) or SFN alone group (P < 0.0014).

CONCLUSIONS

The data suggest that colon cancer cells respond to dietary components differently under different conditions. The effect of vitamin D and SFN is selective and gene-specific in the complex multistep process of colorectal carcinogenesis in vitro. © 2020 Society of Chemical Industry.

Epigenetic Neuropharmacology: Drugs Affecting the Epigenome in the Brain

This review explores how different classes of drugs, including those with therapeutic and abuse potential, alter brain functions and behavior via the epigenome. Epigenetics, in its simplest interpretation, is the study of the regulation of a genes' transcriptional potential. The epigenome is established during development but is malleable throughout life by a wide variety of drugs, with both clinical utility and abuse potential. An epigenetic effect can be central to the drug's therapeutic or abuse potential, or it can be independent from the main effect but nevertheless produce beneficial or adverse side effects. Here, I discuss the various epigenetic effects of main pharmacological drug classes, including antidepressants, antiepileptics, and drugs of abuse.

Death by histone deacetylase inhibitor quisinostat in tongue squamous cell carcinoma via apoptosis, pyroptosis, and ferroptosis

Tongue cancer is one of the most common oral malignancies. Quisinostat is a histone deacetylase inhibitor with antitumor activity. The aim of this study was to evaluate the effects of quisinostat on the viability of tongue squamous cell carcinoma (TSCC) cells (CAL-27, TCA-8113) in vitro and in vivo. Cell viability, cell morphological observation, scratch wound-healing assay, transwell migration assay, transmission electron microscope, flow cytometry and cellular reactive oxygen species were assessed in vitro. The results showed that quisinostat can significantly inhibit the viability, growth and migration of TSCC cells. And quisinostat could significantly induce TSCC cells apoptosis, pyroptosis, and ferroptosis. Quisinostat significantly inhibited tumor tissue growth in animal experiments. Up-regulation of the expression of Bax, cleaved-caspase3, caspase-1, p53, phospho-p53 and down-regulated of the expression of caspase-3, Bcl-2, GPX4 in cell lines and tumor tissues of nude mice were observed by Western blotting analysis. Up-regulation of the expression of caspase-1, Bax, cleaved-caspase3, p53 and down-regulated of the expression of ki67, caspase-3, Bcl-2, GPX4 in tumor tissues of nude mice were observed by immunohistochemistry. TUNEL analysis showed that quisinostat could increase the apoptosis rate in the tumor tissues of nude mice. Up-regulation of the expression of p53 and down-regulated expression of GPX4 in cell lines were observed by immunofluorescent staining, and the expression locations of p53 and GPX4 proteins in TSCC cells were observed. Based on these findings, quisinostat may be a potential drug for the treatment of tongue squamous cell carcinoma.

Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare and heterogeneous group of clinically aggressive diseases associated with poor prognosis. Except for ALK + anaplastic large-cell lymphoma (ALCL), most peripheral T-cell lymphomas are highly malignant and have an aggressive disease course and poor clinical outcomes, with a poor remission rate and frequent relapse after first-line treatment. Aberrant epigenetic alterations play an important role in the pathogenesis and development of specific types of peripheral T-cell lymphoma, including the regulation of the expression of genes and signal transduction. The most common epigenetic alterations are DNA methylation and histone modification. Histone modification alters the level of gene expression by regulating the acetylation status of lysine residues on the promoter surrounding histones, often leading to the silencing of tumour suppressor genes or the overexpression of proto-oncogenes in lymphoma. DNA methylation refers to CpG islands, generally leading to tumour suppressor gene transcriptional silencing. Genetic studies have also shown that some recurrent mutations in genes involved in the epigenetic machinery, including TET2, IDH2-R172, DNMT3A, RHOA, CD28, IDH2, TET2, MLL2, KMT2A, KDM6A, CREBBP, and EP300, have been observed in cases of PTCL. The aberrant expression of miRNAs has also gradually become a diagnostic biomarker. These provide a reasonable molecular mechanism for epigenetic modifying drugs in the treatment of PTCL. As epigenetic drugs implicated in lymphoma have been continually reported in recent years, many new ideas for the diagnosis, treatment, and prognosis of PTCL originate from epigenetics in recent years. Novel epigenetic-targeted drugs have shown good tolerance and therapeutic effects in the treatment of peripheral T-cell lymphoma as monotherapy or combination therapy. NCCN Clinical Practice Guidelines also recommended epigenetic drugs for PTCL subtypes as second-line therapy. Epigenetic mechanisms provide new directions and therapeutic strategies for the research and treatment of peripheral T-cell lymphoma. Therefore, this paper mainly reviews the epigenetic changes in the pathogenesis of peripheral T-cell lymphoma and the advancement of epigenetic-targeted drugs in the treatment of peripheral T-cell lymphoma (PTCL).

CKD-5, a novel pan-histone deacetylase inhibitor, synergistically enhances the efficacy of sorafenib for hepatocellular carcinoma

BACKGROUND

Histone deacetylase inhibitors (HDACIs) have distinctive epigenetic targets involved in hepatocarcinogenesis and chemoresistance. A recent phase I/II study reported the possibility of HDACI as a chemosensitizer in sorafenib-resistant patients. In this study, we evaluated whether CKD-5, a novel pan-HDACI, can potentiate the efficacy of sorafenib.

METHODS

The anticancer effect of CKD-5 with and without sorafenib was evaluated in vitro using an MTS assay with human HCC cells (SNU-3058 and SNU-761) under both normoxic and hypoxic conditions. Microarray analysis was performed to investigate the mechanism of cell death, which was also evaluated by small interfering RNA (siRNA) transfection and subsequent immunoblot assays. In vivo experiments were conducted using two different murine HCC models. C3H mice implanted with MH134 cells and C57BL/6 mice implanted with RIL-175 cells were treated with weekly CKD-5 with and without sorafenib for 2 weeks.

RESULTS

CKD-5 treatment significantly suppressed human HCC cell growth in both normoxic and hypoxic conditions. Microarray analysis and real-time PCR showed that CKD-5 treatment significantly increased peripherin expression in HCC cells and that downregulation of peripherin by siRNA decreased CKD-5-induced apoptosis. The combination of CKD-5 and sorafenib decreased cell viability more effectively than sorafenib or CKD-5 monotherapy in human and murine HCC cells. The effectiveness of the combination therapy was consistently demonstrated in the animal models. Histological and biochemical analyses demonstrated good tolerance of CKD-5 plus sorafenib in vivo.

CONCLUSION

CKD-5 may enhance sorafenib efficacy through epigenetic regulation. The combination of CKD-5 and sorafenib might be a novel therapeutic option for the treatment of HCC.

[Research Progress of Epigenetics in Pathogenesis and Treatment of Malignant Tumors]

表观遗传学修饰与肿瘤的发生发展密切相关，其主要通过DNA甲基化、组蛋白修饰、非编码RNA调控和染色质结构重构等方式对基因功能和表达水平进行调控，从而影响肿瘤的进展。目前针对表观遗传学的药物已经逐渐应用于恶性肿瘤的治疗，常见的药物类型包括DNA甲基转移酶抑制剂和组蛋白去乙酰化酶抑制剂，但此类药物仍存在诸多不足之处广泛的临床应用仍需要进一步的研究，令人鼓舞的是表观遗传药物与多种抗肿瘤药物联合应用已表现出巨大的应用潜力。本文就表观遗传学在恶性肿瘤的发生发展机制和相关药物的新进展进行了综述。

Histone Deacetylase 6 and the Disease Mechanisms of α-Synucleinopathies

The abnormal accumulation of α-Synuclein (α-Syn) is a prominent pathological feature in a group of diseases called α-Synucleinopathies, such as Parkinson’s disease, dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). The formation of Lewy bodies (LBs) and glial cytoplasmic inclusions (GCIs) in neurons and oligodendrocytes, respectively, is highly investigated. However, the molecular mechanisms behind α-Syn improper folding and aggregation remain unclear. Histone deacetylase 6 (HDAC6) is a Class II deacetylase, containing two active catalytic domains and a ubiquitin-binding domain. The properties of HDAC6 and its exclusive cytoplasmic localization allow HDAC6 to modulate the microtubule dynamics, acting as a specific α-tubulin deacetylase. Also, HDAC6 can bind ubiquitinated proteins, facilitating the formation of the aggresome, a cellular defense mechanism to cope with higher levels of misfolded proteins. Several studies report that the aggresome shares similarities in size and composition with LBs and GCIs. HDAC6 is found to co-localize with α-Syn in neurons and in oligodendrocytes, together with other aggresome-related proteins. The involvement of HDAC6 in several neurodegenerative diseases is already under discussion, however, the results obtained by modulating HDAC6 activity are not entirely conclusive. The main goal of this review is to summarize and critically discuss previous in vitro and in vivo data regarding the specific role of HDAC6 in the context of α-Syn accumulation and protein aggregation in α-Synucleinopathies.

Current status of histone deacetylase inhibitors in cutaneous T-cell lymphoma

Cutaneous T cell lymphoma (CTCL) is a non-Hodgkin's lymphoma with a heterogenous presentation and highly variable disease course. The most common subtypes of CTCL are mycosis fungoides (MF) and Sézary Syndrome (SS). Treatment varies based on the stage of the disease with skin directed therapies typically utilized for early stage disease, and systemic therapies employed for more advanced disease. There are few highly effective treatments available, and systemic therapies have limited response rates. Histone deacetylase inhibitors have emerged as mainstream treatments for MF/SS over the past several years. Here, we discuss the mechanism of action of histone deacetylase inhibitors in relation to the pathogenesis of MF/SS, evaluate the clinical trials that led to Food and Drug Administration approval of two of the histone deacetylase inhibitors for MF/SS and describe the results for those still under investigation. Additionally, we discuss the potential for combination therapies in order to optimize outcomes of treatment with histone deacetylase inhibitors.

Expression of Stromal Progesterone Receptor and Differential Methylation Patterns in the Endometrium May Correlate with Response to Progesterone Therapy in Endometrial Complex Atypical Hyperplasia

Progesterone therapy is a viable treatment for complex atypical hyperplasia (CAH) and endometrial adenocarcinoma, though reliable molecular determinants of response are not available. To explore if analysis of pre-therapy endometrial biopsies could yield biomarkers of response to progesterone, patients with CAH or adenocarcinoma undergoing treatment with progestins were included in this cross-sectional study. Immunohistochemistry for progesterone receptor (PR) was performed. Manual PR expression scores (PRES) were first calculated for biopsies by counting PR-positive nuclei in 12 sensitive vs 9 resistant samples. Significant differences in manual PRES were detected in the stroma (p < 0.01) and total endometrium (p < 0.01) for sensitive vs resistant patients. Manual PRES in the stroma had the highest accuracy in segregating sensitive vs resistant patients (96%). Differences in epithelial PRES were not significant. To validate these findings, a correlation between manual PRES and visual PRES was performed in the 21 patients. An additional 11 patients were analyzed to test if visual PRES would be predictive of response to progesterone. Visual PRES in epithelia and stroma in the 32 specimens was calculated. Significant differences in visual PRES were detected in the stroma for sensitive vs resistant samples (p < 0.01), while differences in epithelial and total endometrium were not significant. Whole genome bisulfite sequencing was performed on DNA isolated using pre-therapy biopsies from 6 sensitive and 6 resistant patients in this cohort. Differentially methylated regions were identified in the stroma and epithelium when evaluating sensitive vs resistant samples. Pathways involved in cell adhesion demonstrated the greatest difference in methylation in these samples.

NCI 6896: a phase I trial of vorinostat (SAHA) and isotretinoin (13-cis retinoic acid) in the treatment of patients with advanced renal cell carcinoma

Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumor sensitivity to retinoids and have synergistic anti-tumor activity when combined. We performed a Phase I clinical trial to evaluate the safety and preliminary efficacy of combining the oral HDAC inhibitor vorinostat and isotretinoin in patients with advanced renal cell carcinoma (RCC). Vorinostat was administered at 300 mg orally twice daily in combination with escalating doses of isotretinoin for 3 consecutive days per week. A standard 3 + 3 dose escalation design was used. Dose limiting toxicities (DLT) were assess during the first cycle to determine the maximum tolerated dose (MTD). Fourteen patients enrolled on the trial of which 12 were evaluable for toxicity (6 cohort 1; 3 cohort 2; 3 cohort 3) and 11 for tumor response. One patient in cohort 1 experienced a DLT (grade 3 depression). Common grade 1-2 toxicities included fatigue and GI effects (nausea, diarrhea, anorexia). MTD was established as vorinostat 300 mg with isoretinoin 0.5 mg/kg twice daily 3 days per week. Best responses in evaluable patients included 1 partial response and 9 stable disease, lasting a median of 3.7 months (range 1.8-10.4 months). The combination of vorinostat and isotretinoin is safe, tolerable and associated with responses in patients with refractory metastatic RCC.

Mycosis fungoides and Sézary syndrome: 2019 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, skin-directed therapies are preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies. These include biologic-response modifiers, histone deacetylase (HDAC) inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Quantitative Proteomic Analysis Reveals the Sites Related to Acetylation and Mechanism of ACY-1215 in Acute Liver Failure Mice

Background: ACY-1215 is a well-known selective histone deacetylase 6 (HDAC6) inhibitor, and it has been considered as a potential therapeutic drug in inflammatory diseases, including acute liver failure (ALF). However, little is known about the impact of ACY-1215 treatment on histone lysine acetylation and proteome in ALF. In this study, we aim to investigate whether ACY-1215 has inhibitory effects and mechanism on the necrosis of hepatocytes; moreover, the impact of ACY-1215 treatment on histone lysine acetylation still needs further elucidation.

Methods: Male C57/BL6 mice were divided into normal, model, and ACY-1215 groups. ACY-1215 (25 mg/kg) and same amounts of saline were injected intraperitoneally to the mice before the establishment of ALF model induced by lipopolysaccharide (LPS) (100 µg/kg) combined with D-gal (400 mg/kg). All animals were sacrificed after 24 h. In this study, detection programs, including quantitative proteomic analysis, transmission electron microscopy (TEM) micrographs, pathological staining, protein expression, the detection of reactive oxygen species (ROS) as well as glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) measurement.

Results: The function of liver and the necrosis of hepatocytes in ALF mice were significantly normalized by ACY-1215 pretreatment. The quantitative proteomic analysis revealed that ACY-1215-restrained oxidative phosphorylation normalized the function respiratory electron-transport chain in the mitochondria. Moreover, pretreatment of ACY-1215 not only normalized the structure of mitochondria but also inhibited the generation of reactive oxygen species (ROS).

Conclusions: ACY-1215 was able to inhibit necrosis of hepatocytes in ALF mice through regulating the mitochondrial-mediated oxidative stress, and we identified the common sites related to acetylation level.

Overview of Targeted Drugs for Mature B-Cell Non-hodgkin Lymphomas

The improved knowledge of pathogenetic mechanisms underlying lymphomagenesis and the discovery of the critical role of tumor microenvironments have enabled the design of new drugs against cell targets and pathways. The Food and Drug Administration (FDA) has approved several monoclonal antibodies (mAbs) and small molecule inhibitors (SMIs) for targeted therapy in hematology. This review focuses on the efficacy results of the currently available targeted agents and recaps the main ongoing trials in the setting of mature B-Cell non-Hodgkin lymphomas. The objective is to summarize the different classes of novel agents approved for mature B-cell lymphomas, to describe in synoptic tables the results they achieved and, finally, to draw future scenarios as we glimpse through the ongoing clinical trials. Characteristics and therapeutic efficacy are summarized for the currently approved mAbs [i.e., anti-Cluster of differentiation (CD) mAbs, immune checkpoint inhibitors, chimeric antigen receptor (CAR) T-cell therapy, and bispecific antibodies] as well as for SMIs i.e., inhibitors of B-cell receptor signaling, proteasome, mTOR BCL-2 HDAC pathways. The biological disease profiling of B-cell lymphoma subtypes may foster the discovery of innovative drug strategies for improving survival outcome in lymphoid neoplasms, as well as the trade-offs between efficacy and toxicity. The hope for clinical advantages should carefully be coupled with mindful awareness of the potential pitfalls and the occurrence of uneven, sometimes severe, toxicities.

The Histone Deacetylase Inhibitor AN7, Attenuates Choroidal Neovascularization in a Mouse Model

: Choroidal neovascularization (CNV) is a complication of age-related macular degeneration and a major contributing factor to vision loss. In this paper, we show that in a mouse model of laser-induced CNV, systemic administration of Butyroyloxymethyl-diethyl phosphate (AN7), a histone deacetylase inhibitor (HDACi), significantly reduced CNV area and vascular leakage, as measured by choroidal flatmounts and fluorescein angiography. CNV area reduction by systemic AN7 treatment was similar to that achieved by intravitreal bevacizumab treatment. The expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), and the endothelial cells marker CD31, was lower in the AN7 treated group in comparison to the control group at the laser lesion site. In vitro, AN7 facilitated retinal pigmented epithelium (RPE) cells tight junctions' integrity during hypoxia, by protecting the hexagonal pattern of ZO-1 protein in the cell borders, hence reducing RPE permeability. In conclusion, systemic AN7 should be further investigated as a possible effective treatment for CNV.

Histone Deacetylases (HDACs) Guided Novel Therapies for T-cell lymphomas

T-cell lymphomas are a heterogeneous group of cancers with different pathogenesis and poor prognosis. Histone deacetylases (HDACs) are epigenetic modifiers that modulate many key biological processes. In recent years, HDACs have been fully investigated for their roles and potential as drug targets in T-cell lymphomas. In this review, we have deciphered the modes of action of HDACs, HDAC inhibitors as single agents, and HDACs guided combination therapies in T-cell lymphomas. The overview of HDACs on the stage of T-cell lymphomas, and HDACs guided therapies both as single agents and combination regimens endow great opportunities for the cure of T-cell lymphomas.

Crosstalk between Epigenetic Modulations in Valproic Acid Deactivated Hepatic Stellate Cells: An Integrated Protein and miRNA Profiling Study

Reverting activated hepatic stellate cells (HSCs) to less activation or quiescent status is a promising strategy for liver fibrosis. Histone deacetylase inhibitor (HDACI) could suppress HSCs activation. Our previous study demonstrated a critical role of miRNAs in HSCs activation. Here, we explored the involvement of miRNAs in HDACI induced HSCs deactivation. Human cell line LX2 that resembled activated HSCs was treated with an HDACI - valproic acid (VPA). The effects of VPA on the protein and miRNA profile of LX2 were comprehensively analyzed by iTraq quantitative proteomics and miRNA microarray. The interaction between miRNA and proteins was investigated systematically. The biofunctions of differentially expressed proteins and miRNA targeted proteins were annotated. VPA treatment attenuated the activation phenotype of LX2. In VPA treated LX2, among 1548 quantified proteins, only 86 proteins were differentially expressed (VPA-proteins). While among 282 high-abundance miRNAs, 123 were differentially expressed (VPA-miRNAs), with 104 down-regulated and 19 up-regulated. The top biofunctions of VPA-proteins were closely related to HSCs activation, including cell death and survival, cell movement, cellular growth and proliferation. Furthermore, 22 out of the 36 VPA-proteins involved in cell death and survival, and 19 out of the 30 VPA-proteins involved in cellular movement were predicted targets of VPA-miRNAs. A direct regulatory effect of histone acetylation on miRNA expression was also established. In conclusion, our data provided the molecular mechanisms for VPA induced HSCs deactivation at the protein level and suggested crosstalk between histone acetylation and miRNAs in the inhibitory effects of HDACI on HSCs activation.

Current Status of HDAC Inhibitors in Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of lymphomas that are characterized by primary skin involvement. Mycosis fungoides (MF) and Sézary syndrome (SS), the two most common subtypes of CTCL, can be difficult to manage clinically as there are few effective treatment options available. Recently, histone deacetylase inhibitors (HDACi) have emerged as promising therapies with favorable adverse effect profiles, compared with traditional chemotherapies. In this article, we review the published literature to evaluate the role of HDACi in the treatment of CTCL. Specifically, we (1) briefly discuss the molecular rationale for the use of HDACi in CTCL; (2) compare the efficacy, tolerability, and adverse effects of HDACi; (3) review the cardiac safety data; and (4) discuss optimization of therapy with HDACi in the treatment of CTCL.

The HDAC Inhibitor Quisinostat (JNJ-26481585) Supresses Hepatocellular Carcinoma alone and Synergistically in Combination with Sorafenib by G0/G1 phase arrest and Apoptosis induction

The high activity of Histone deacetylases (HDACs) in hepatocellular carcinoma (HCC) usually positively correlates with poor prognosis of patients. Accordingly histone deacetylases inhibitors (HDACis) are considered to be potential agents treating patients with HCC. In our study, we evaluated effect of quisinostat alone and in combination with sorafenib in HCC cells via inducing G0/G1 phase arrest through PI3K/AKT/p21 pathway and apoptosis by JNK/c-Jun/caspase3 pathway in vitro and in vivo. The proliferation assay and flow cytometry were used to measure the viability, cell cycle and apoptosis. And Western blot assay was carried out to determine expression alternations of related proteins. Moreover HCCLM3 xenograft was further performed to detect antitumor effect of quisinostat in vivo. Here, we found that quisinostat impeded cell proliferation, and remarkably induced G0/G1 phase arrest and apoptosis in HCC cells in a dose-dependent manner. G0/G1 phase arrest was observed by alterations in PI3K/AKT/p21 proteins. Meanwhile the JNK, c-jun and caspase-3 were activated by quisinostat in a dose-dependent manner. Correspondingly quisinostat facilitated G0/G1 cycle arrest and apoptosis in HCC cells through PI3K/AKT/p21 pathways and JNK/c- jun/caspase3 pathways. Moreover, the potent tumor-suppressive effects facilitated by quisinostat, was significantly potentiated by combination with sorafenib in vitro and vivo. The combination treatment of quisinostat and sorafenib markedly suppressed cell proliferation and induced apoptosis in a synergistic manner. Moreover the therapy of quisinostat combined with sorafenib could apparently decrease tumor volume of a HCCLM3 xenograft model. Our study indicated that quisinostat, as a novel chemotherapy for HCC, exhibited excellent antitumor activity in vitro and vivo, which was even enhanced by the addition of sorafenib, implying combination of quisinostat with sorafenib a promising and alternative therapy for patients with advanced hepatocellular carcinoma.

The Therapeutic Strategy of HDAC6 Inhibitors in Lymphoproliferative Disease

Histone deacetylases (HDACs) are master regulators of chromatin remodeling, acting as epigenetic regulators of gene expression. In the last decade, inhibition of HDACs has become a target for specific epigenetic modifications related to cancer development. Overexpression of HDAC has been observed in several hematologic malignancies. Therefore, the observation that HDACs might play a role in various hematologic malignancies has brought to the development of HDAC inhibitors as potential antitumor agents. Recently, the class IIb, HDAC6, has emerged as one potential selective HDACi. This isoenzyme represents an important pharmacological target for selective inhibition. Its selectivity may reduce the toxicity related to the off-target effects of pan-HDAC inhibitors. HDAC6 has also been studied in cancer especially for its ability to coordinate a variety of cellular processes that are important for cancer pathogenesis. HDAC6 has been reported to be overexpressed in lymphoid cells and its inhibition has demonstrated activity in preclinical and clinical study of lymphoproliferative disease. Various studies of HDAC6 inhibitors alone and in combination with other agents provide strong scientific rationale for the evaluation of these new agents in the clinical setting of hematological malignancies. In this review, we describe the HDACs, their inhibitors, and the recent advances of HDAC6 inhibitors, their mechanisms of action and role in lymphoproliferative disorders.

Histone deacetylase inhibitors upregulate Snail via Smad2/3 phosphorylation and stabilization of Snail to promote metastasis of hepatoma cells

Hepatocellular carcinoma (HCC) remains the third most common cause of cancer-related mortality. Resection and transplantation are the only curative treatments available, but are greatly hampered by high recurrence rates. Histone deacetylase inhibitors (HDACIs) are considered to be promising anticancer agents in drug development. Currently, four HDACIs have been granted Food and Drug Administration (FDA) approval for cancer. HDACIs have shown significant efficacy in hematological malignancies. However, they have limited effects in epithelial cell-derived cancers, including HCC, and the mechanisms of these are not elucidated. In this study, our results demonstrated that HDACIs were able to induce epithelial-mesenchymal transitions (EMT) in hepatoma cells which are believed to trigger tumor cell invasion and metastasis. We found that HDACIs promoted the expression of Snail and Snail-induced EMT was critical for HDACI-initiated invasion and metastasis. We indicated that HDACIs upregulated Snail in two ways. Firstly, HDACIs upregulated Snail at the transcriptional level by promoting Smad2/3 phosphorylation and nuclear translocation, then combined with the promoter to activate the transcription of Snail. Secondly, we showed that HDACIs regulated the stabilization of Snail via upregulating the expression of COP9 signalosome 2 (CSN2), which combined with Snail and exposed its acetylation site, then promoted acetylation of Snail, thereby inhibiting its phosphorylation and ubiquitination to repress the degradation of Snail. All these results highlighted that HDACIs have limited effects in HCC, and the use of HDACIs combined with other targeted strategies to inhibit EMT, which explored in this study is a promising treatment method for treating HCC.

New 5-Aryl-Substituted 2-Aminobenzamide-Type HDAC Inhibitors with a Diketopiperazine Group and Their Ameliorating Effects on Ischemia-Induced Neuronal Cell Death

We previously synthesized new 5-thienyl-substituted 2-aminobenzamide-type HDAC1, 2 inhibitors with the (4-ethyl-2,3-dioxopiperazine-1-carboxamido) methyl group. K-560 (1a) protected against neuronal cell death in a Parkinson’s disease model by up-regulating the expression of XIAP. This finding prompted us to design new K-560-related compounds. We examined the structure activity relationship (SAR) for the neuronal protective effects of newly synthesized and known K-560 derivatives after cerebral ischemia. Among them, K-856 (8), containing the (4-methyl-2,5-dioxopiperazin-1-yl) methyl group, exhibited a promising neuronal survival activity. The SAR study strongly suggested that the attachment of a monocyclic 2,3- or 2,5-diketopiperazine group to the 2-amino-5-aryl (but not 2-nitro-5-aryl) scaffold is necessary for K-560-related compounds to exert a potent neuroprotective effect.

Novel Therapeutics in Glaucoma Management

BACKGROUND

Glaucoma is a progressive optic neuropathy characterized by retinal ganglion cell death and alterations of visual field. Elevated intraocular pressure (IOP) is considered the main risk factor of glaucoma, even though other factors cannot be ruled out, such as epigenetic mechanisms.

OBJECTIVE

An overview of the ultimate promising experimental drugs to manage glaucoma has been provided.

RESULTS

In particular, we have focused on purinergic ligands, KATP channel activators, gases (nitric oxide, carbon monoxide and hydrogen sulfide), non-glucocorticoid steroidal compounds, neurotrophic factors, PI3K/Akt activators, citicoline, histone deacetylase inhibitors, cannabinoids, dopamine and serotonin receptors ligands, small interference RNA, and Rho kinase inhibitors.

CONCLUSIONS

The review has been also endowed of a brief chapter on last reports about potential neuroprotective benefits of anti-glaucoma drugs already present in the market.

Comparison of the anticancer properties of a novel valproic acid prodrug to leading histone deacetylase inhibitors

The HDAC inhibitory activity of valproic acid (VPA) has led to on-going evaluation of it as an anticancer agent. The histone deacetylase (HDAC) inhibitor AN446, a prodrug of VPA, releases the acid upon metabolic degradation. AN446 is >60-fold more potent than VPA in killing cancer cells in vitro. Herein, we compare the activities of AN446, as an anticancer agent, to those of representative types from each of the four major classes of HDAC inhibitors (HDACIs): vorinostat, romidepsin, entinostat, and VPA. AN446 exhibited the greatest selectivity and HDAC inhibitory activity against cancer cells. In glioblastoma cells only AN446, and in MDA-MB-231 cells only AN446 and VPA interacted in synergy with doxorubicin (Dox). AN446 was superior to the studied HDACIs in inducing DNA-damage in cancer cells, while in normal astrocytes and cardiomyoblasts AN446 was the least toxic. AN446 was the only HDACI tested that exhibited selective HDAC inhibitory activity that was high in cancer cells and low in noncancerous cells. This discriminating inhibition correlated with the toxicity of the HDACIs, suggesting that their effects could be attributed to HDAC inhibition. In cardiomyoblasts, the HDACIs tested, except for AN446, hampered DNA repair by reducing the level of Rad 51. VPA and AN446 were the most effective HDACIs in inhibiting in vitro migration and invasion. The advantages of AN446 shown here, position it as a potentially improved HDACI for treatment of glioblastoma and triple negative breast cancer.

Induction of colon and cervical cancer cell death by cinnamic acid derivatives is mediated through the inhibition of Histone Deacetylases (HDAC)

Recent studies from our group and many others have shown the ability of histone deacetylase (HDAC) inhibitors for retarding the growth of carcinomas of cervix, colon and rectum in vitro. A search for naturally occurring HDAC inhibitors continues due to the adverse effects associated with known HDAC inhibitors like SAHA and TSA. Therefore in the current study, naturally occurring cinnamic acids derivatives were screened for HDAC inhibitory effect using in silico docking method which identified cinnamic acids as potential candidates. Cinnamic acids (CA) are naturally occurring phenolic compounds known to exhibit anticancer properties. However, it is not clearly known whether the anticancer properties of CA derivatives are due to the inhibition of oncogenic HDACs, if so how the efficacy varies among various CA derivatives. Hence, the HDAC inhibitory potential of CA derivatives containing increasing number of hydroxylic groups or methoxy moieties was determined using Discovery Studio software and the most potent CA derivatives tested ex vivo (biochemical assay) as well as in vitro (using cell based assay). Among CA derivatives tested, dihydroxy cinnamic acid (DHCA, commonly known as caffeic acid) exhibited better interactions with HDAC2 (compared to other isoforms) in silico and inhibited its activity ex vivo as well as in vitro. Targeted reduction of HDAC activity using DHCA induced death of cancer cells by (a) generating reactive oxygen species, (b) arresting cells in S and G2/M phases; and (c) induction of caspase-3 mediated apoptosis. In conclusion, we demonstrated that DHCA inhibited cancer cell growth by binding to HDAC followed by the induction of apoptosis.

Diffuse large B-cell lymphoma: can genomics improve treatment options for a curable cancer?

Gene-expression profiling and next-generation sequencing have defined diffuse large B-cell lymphoma (DLBCL), the most common lymphoma diagnosis, as a heterogeneous group of subentities. Despite ongoing explosions of data illuminating disparate pathogenic mechanisms, however, the five-drug chemoimmunotherapy combination R-CHOP remains the frontline standard treatment. This has not changed in 15 years, since the anti-CD20 monoclonal antibody rituximab was added to the CHOP backbone, which first entered use in the 1970s. At least a third of patients are not cured by R-CHOP, and relapsed or refractory DLBCL is fatal in ∼90%. Targeted small-molecule inhibitors against distinct molecular pathways activated in different subgroups of DLBCL have so far translated poorly into the clinic, justifying the ongoing reliance on R-CHOP and other long-established chemotherapy-driven combinations. New drugs and improved identification of biomarkers in real time, however, show potential to change the situation eventually, despite some recent setbacks. Here, we review established and putative molecular drivers of DLBCL identified through large-scale genomics, highlighting among other things the care that must be taken when differentiating drivers from passengers, which is influenced by the promiscuity of activation-induced cytidine deaminase. Furthermore, we discuss why, despite having so much genomic data available, it has been difficult to move toward personalized medicine for this umbrella disorder and some steps that may be taken to hasten the process.

Histone deacetylase 6 inhibitor ACY-1215 protects against experimental acute liver failure by regulating the TLR4-MAPK/NF-κB pathway

Histone deacetylase 6 (HDAC6) is considered a new target for anticancer, anti-inflammatory, and neurodegenerative treatment. ACY-1215 is a selective histone deacetylase 6 inhibitor, and it has been recognized as a potential anticancer and anti-inflammation drug. The aim of our study was to investigate whether ACY-1215 has protective effects on acute liver failure (ALF) in mice and explore its potential mechanism. Male C57/BL6 mice were divided into normal, model, and ACY-1215 groups. ACY-1215 (25mg/kg) and same amounts of saline were given to mice. After 2h, the ALF models were induced by lipopolysaccharide (LPS, 100μg/kg) combined with D-galactosamine (D-gal, 400mg/kg). All animals were killed after 24h. The expressions of HDAC6 were determined by western blotting and RT-PCR assay. The expression levels of inflammatory cytokines were detected by ELISA and RT-PCR. The protein expression of Toll-like receptor 4 (TLR4), mitogen-activated protein kinase (MAPK), and nuclear factor κB (NF-κB) species were determined by western blot. The mortality of mice with ALF induced by LPS and D-gal was significantly decreased by ACY-1215 pretreatment. Procedures to manage ALF caused adversely affected liver histology and function; this damage was repaired by pretreatment of ACY-1215. ACY-1215 treatment also attenuated the serum and messenger RNA levels of the proinflammatory cytokines. Pretreatment of ACY-1215 significantly decreased the protein expression of TLR4 and the activation of MAPK and NF-κB signalling pathways. ACY-1215 has potential therapeutic value in mice with ALF by directly inhibiting inflammatory response via regulation of the TLR4-MAPK/NF-kB pathway.

Drug Discovery and Chemical Biology of Cancer Epigenetics

Comprehensive whole-exome sequencing, DNA copy-number determination, and transcriptomic analyses of diverse cancers have greatly expanded our understanding of the biology of many tumor types. In addition to mutations in the common cell-of-origin specific driver mutations, these studies have also revealed a large number of loss-of-function and gain-of-function mutations in chromatin-modifying proteins (CMPs). This has revealed that epigenetic dysregulation is a common feature of most pediatric and adult cancers. Many specific and potent inhibitors have been developed for multiple CMP classes, which have assisted in elucidating the role of epigenetics as well as epigenetic vulnerabilities in these cancer types. Clinical trials with numerous CMP inhibitors are also currently in progress to evaluate the therapeutic potential of epigenetic inhibitors. In this review, we aim to provide a summary of genetic mutations in epigenetic genes and a review of CMP inhibitors suitable for preclinical studies or currently in clinical trials. Additionally, we highlight the CMPs for which potent inhibitors have not been developed and additional research focus should be dedicated.

Cutaneous T-cell lymphoma: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.